In a traditional knee arthroplasty surgery, the diseased bone and/or cartilage of a patient is generally removed and replaced with a prosthetic implant. A surgeon may prepare the bone using a hand-held oscillating saw blade, for instance, which generally results in a series of planar bone surface resections. Additionally, the surgeon may use a drill, broach or tamp instrument to make cylindrical holes into the bone to accommodate peg fixation features on the implant. The planar bone resections and cylindrical bone holes are generally oriented to interface with generally flat bone contacting surfaces and pegs of a prosthetic implant.
In such arthroplasty surgeries, the cartilage and/or bone of a patient may be prepared by a surgeon using conventional manual instrumentation. The instrumentation used may include, for example, planar resection guides, oscillating saws, drills, chisels, punches and reamers.
Robotic surgery may also be used in arthroplasty procedures, as well as in many different medical applications. The use of a robotically controlled bone preparation system allow for increased accuracy and repeatability of bone preparation. Rotational preparation instruments may be used during robotic surgery to prepare the bone and/or cartilage surfaces.
Bone preparation using these known methods generally provides surfaces of variable accuracy. Further, implant surfaces are generally prepared with the same level of consistency across the entire prepared bone surface. These methods of bone preparation may have a negative effect on the initial fixation of a cementless implant. If the surface does not provide a stable base for a cementless implant when initially fixed to the bone, the long term success of bone ingrowth/ongrowth onto the implant may be compromised due to micromotion, which may lead to fibrous ingrowth and subsequent bone resorption.
With advancements in robotically controlled bone preparation systems, bone preparation with specifically designed regions having increased levels of accuracy are now considered. Therefore, robotic bone preparation enables select aspects of the bone to be prepared at a generally more accurate and “tighter” tolerance compared with alternate methods of bone preparation. The degree of accuracy to which a prosthetic implant is implanted on a prepared or resected bone through robotic control depends on several factors. Among those factors include the tolerance to which the prosthetic implant is manufactured or know, the tolerance of any required tracking equipment used to position the robotic arm, and the tolerances of the robotic arm itself.